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Page 1511 of 2547
How to create an immutable class with mutable object references in Java?
Immutable objects are those objects whose states cannot be changed once initialized. Sometimes it is necessary to make an immutable class as per the requirement. For example, All primitive wrapper classes (Integer, Byte, Long, Float, Double, Character, Boolean and Short) are immutable in Java. String class is also an immutable class.To create a custom immutable class we have to do the following stepsDeclare the class as final so it can’t be extended.Make all fields private so that direct access is not allowed.Do not provide setter methods (methods that modify fields) for variables, so that it can not be set.Make all mutable ...
Read MoreWhen can we use intern() method of String class in Java?
The intern() method of String class can be used to deal with the string duplication problems in Java. Using intern() we can save a lot of memory consumed by duplicate string instances. A string is duplicate if it contains the same content as another string but it can be occupied different memory locations.We know that JVM maintains a separate heap memory for string literals for the performance. Once we declare a string literal it will go to this pool and if another variable is assigned with the same literal value, it will be picked from the pool instead of creating a new ...
Read MoreThe isEmpty() method of Java AbstractCollection class
The isEmpty() method of the AbstractCollection class checks whether the collection is empty or not i.e. whether it has zero elements. It returns if the Collectionn has no elements.The syntax is as follows −public boolean isEmpty()To work with AbstractCollection class in Java, import the following package −import java.util.AbstractCollection;The following is an example to implement AbstractCollection isEmpty() method in Java −Exampleimport java.util.ArrayList; import java.util.AbstractCollection; public class Demo { public static void main(String[] args) { AbstractCollection absCollection = new ArrayList(); absCollection.add("Laptop"); absCollection.add("Tablet"); absCollection.add("Mobile"); absCollection.add("E-Book Reader"); ...
Read Morematch max_size() function in C++ STL
The match max_size() function in C++ STL returns the maximum number of elements in the match_results object that can be held by the match container.This function does not accept a parameter.Example Code#include #include using namespace std; int main() { match_results m; cout
Read MoreThe iterator() method of Java AbstractCollection class
The iterator() method of the AbstractCollection class in Java is used to return an iterator over the elements contained in this collection.The syntax is as follows −public abstract Iterator iterator()To work with AbstractCollection class in Java, import the following package −import java.util.AbstractCollection;For Iterator, import the following package −import java.util.Iterator;The following is an example to implement the AbstractCollection iterator() method in Java −Exampleimport java.util.Iterator; import java.util.ArrayList; import java.util.AbstractCollection; public class Demo { public static void main(String[] args) { AbstractCollection absCollection = new ArrayList(); absCollection.add("Laptop"); absCollection.add("Tablet"); absCollection.add("Mobile"); ...
Read MoreWhat is StringJoiner class in Java 8?
The StringJoiner class in Java 8 constructs a sequence of characters. This sequence is separated by a delimiter and optionally starting with a supplied prefix and ending with a supplied suffix.The following are the constructors of the StringJoiner class:StringJoiner(CharSequence delimiter): This constructor constructs a StringJoiner with no characters in it and with no prefix or suffix. It used the copy of the supplied delimiter.StringJoiner(CharSequence delimiter, CharSequence prefix, CharSequence suffix) This constructor constructs a StringJoiner with no characters in it. It uses the copies of the supplied prefix, delimiter and suffix.The syntax is as follows:public final class StringJoiner extends ObjectHere, class ...
Read MoreWhat is EOFException in Java? How do we handle it?
While reading the contents of a file in certain scenarios the end of the file will be reached in such scenarios a EOFException is thrown.Especially, this exception is thrown while reading data using the Input stream objects. In other scenarios a specific value will be thrown when the end of file reached.Let us consider the DataInputStream class, it provides various methods such as readboolean(), readByte(), readChar() etc.. to read primitive values. While reading data from a file using these methods when the end of file is reached an EOFException is thrown.ExampleFollowing program demonstrates how to handle the EOFException in Java.import ...
Read MoreA Reluctant qualifier in Java Regular Expressions
The reluctant qualifier starts with the shortest string size as possible. If a match is found by the engine, the process continues to find more matches otherwise the engine adds a character to the searched string section and tries again. This continues until a match is obtained or the string is used up.The regex "B+?" is used to find the match in the string "SkyIsBlue".A program that demonstrates this is given as follows:Exampleimport java.util.regex.Matcher; import java.util.regex.Pattern; public class Demo { public static void main(String args[]) { String regex = "B+?"; String str = ...
Read MoreIntStream findAny() method in Java
The findAny() method of the IntStream class in Java is used to return an OptionalInt describing some element of the stream, or an empty OptionalInt if the stream is empty.The syntax is as follows −OptionalInt findAny()Here, OptionalInt is a container object which may or may not contain an int value.Create an IntStream and add some elements −IntStream intStream = IntStream.of(20, 35, 50, 60, 80, 100);Now, return any of the element of the stream using findAny() in Java −OptionalInt res = intStream.findAny();The following is an example to implement IntStream findAny() method in Java −Exampleimport java.util.*; import java.util.stream.IntStream; public class Demo ...
Read MoreThe listIterator() method of CopyOnWriteArrayList in Java starting at a specified position
The listIterator() method CopyOnWriteArrayList class returns a list iterator over the elements in this list, beginning at the specified position in the list.The syntax is as followspublic ListIterator listIterator(int index)Here, index is the index of the first element to be returned from the list iterator.To work with CopyOnWriteArrayList class, you need to import the following packageimport java.util.concurrent.CopyOnWriteArrayList;The following is an example to implement CopyOnWriteArrayList class listIterator() method in Java. We have set the index as 3, therefore, the list would be iterated from index 3Exampleimport java.util.Iterator; import java.util.ListIterator; import java.util.concurrent.CopyOnWriteArrayList; public class Demo { public static void main(String[] args) ...
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